Mechanical Engineering - Engineer's degreehttp://hdl.handle.net/1721.1/7851
Thu, 26 Feb 2015 17:40:57 GMT2015-02-26T17:40:57ZCOLREGS-compliant autonomous collision avoidance using multi-objective optimization with interval programminghttp://hdl.handle.net/1721.1/92956
COLREGS-compliant autonomous collision avoidance using multi-objective optimization with interval programming
Woerner, Kyle
High contact density environments are becoming ubiquitous in autonomous marine vehicle (AMV) operations. Safely managing these environments and their mission greatly taxes platforms. AMV collisions will likely increase as contact density increases. In situations where AMVs are not performing a collaborative mission but are using shared physical space such as multiple vehicles in the same harbor, a high demand exists for safe and efficient operation to minimize mission track deviations while preserving the safety and integrity of mission platforms. With no existing protocol for collision avoidance of AMVs, much effort to date has focused on individual ad hoc collision avoidance approaches that are self-serving, lack the uniformity of fleet-distributed protocols, and disregard the overall fleet efficiency when scaled to being in a contact-dense environment. This research shows that by applying interval programming and a collision avoidance protocol such as the International Regulations for Prevention of Collisions at Sea (COLREGS) to a fleet of AMVs operating in the same geographic area, the fleet achieves nearly identical efficiency concurrent with significant reductions in the collisions observed. A basic collision avoidance protocol was analyzed against a COLREGS-based algorithm while parameters key to collision avoidance were studied using Monte Carlo methods and regression analysis of both real-world and simulated statistical data. A testing metric was proposed for declaring AMVs as "COLREGS-compliant" for at-sea operations. This work tested five AMVs simultaneously with COLREGS collision avoidance-the largest test known to date.
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.; Cataloged from student-submitted PDF version of thesis.; Includes bibliographical references (pages 158-160).
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/1721.1/929562014-01-01T00:00:00ZDesign and assessment of a super high speed, hybrid hydrofoil/SWATH crew boathttp://hdl.handle.net/1721.1/92221
Design and assessment of a super high speed, hybrid hydrofoil/SWATH crew boat
Georgiadis, Vasileios
This thesis presents the preliminary design and assessment of Wavecutter, an innovative super high speed, hybrid hydrofoil/SWATH crew boat. The intended mission of the vessel is the very-fast transportation of crew and cargo, to and from offshore installations. The design builds on Brizzolara's unmanned high speed hybrid SWATH/hydrofoil vessel concept (Brizzolara, 2010), maintaining the dual operating mode: foilborne to reach top speed of 85 knots in moderate sea states and a displacement SWATH to sail in the higher sea states. This vessel is expanding the family of unmanned hybrid SWATH vessels of Brizzolara and Chryssostomidis to include manned vessels (Brizzolara & Chryssostomidis, 2013). The special hydrofoil profile recently optimized and verified by model tests in free-surface cavitation tunnel, has been adopted, to ensure high lift to drag ratios and avoid typical instability phenomena of conventional super-cavitating hydrofoils (Brizzolara, 2013). The surface piercing configuration of the hydrofoils was adopted in order to make the vessel inherently stable, without the use of control mechanisms. The general design phase was focused on the integration of the manned module, internal arrangements, weight estimation, speed profile determination and engine selection. The hydrofoil design phase limits on resizing the four surface-piercing super-cavitating hydrofoils to keep the vessel even keel at maximum speed. To achieve this, the front foils need to have a larger size than the aft ones, due to the trim moment produced by the turbo-jet thrust force. The feasibility assessment phase in foil borne mode confirmed the static stability of the vessel and good seaworthiness in waves. It is recommended that future work be conducted with CFD simulations in unsteady conditions, to obtain a more accurate understanding of the vessel's dynamic behavior.
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Cataloged from PDF version of thesis.; Includes bibliographical references (page 80).
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/1721.1/922212014-01-01T00:00:00ZMechanical characterization of lithium-ion battery micro components for development of homogenized and multilayer material modelshttp://hdl.handle.net/1721.1/92133
Mechanical characterization of lithium-ion battery micro components for development of homogenized and multilayer material models
Miller, Kyle M. (Kyle Mark)
The overall battery research of the Impact and Crashworthiness Laboratory (ICL) at MIT has been focused on understanding the battery's mechanical properties so that individual battery cells and battery packs can be characterized during crash events. The objective of this research is to better understand the battery component (electrode and separator) properties under different loading conditions. In this work, over 200 tests were conducted on battery components. These tests include uniaxial stress, biaxial punch, multilayer, single layer, short-circuit testing, wet vs dry specimen testing, strain rate testing, and more. Additionally, a scanning electron microscope was used to view the battery components at a micro level for the purpose of better understanding the aforementioned test results. During these tests, it was observed that many of the electrodes in the Li-ion batteries are damaged during the battery manufacturing process. Also, the two methods of manufacturing battery separator were analyzed and their resulting mechanical properties were characterized. These results will be used to further refine and validate a high-level, robust, and accurate computational tool to predict strength, energy absorption, and the onset of electric short circuit of batteries under real-world crash loading situations. The cell deformation models will then be applied to the battery stack and beyond, thereby enabling rationalization of greater optimization of the battery pack/vehicle combination with respect to tolerance of battery crush intrusion behavior. Besides improving crash performance, the finite element models contribute substantially to the reduction of the cost of prototyping and shorten the development cycle of new electric vehicles.
Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Cataloged from PDF version of thesis.; Includes bibliographical references (page 60).
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/1721.1/921332014-01-01T00:00:00ZDesign space exploration and optimization using modern ship design toolshttp://hdl.handle.net/1721.1/92124
Design space exploration and optimization using modern ship design tools
Jones, Adam T. (Adam Thomas)
Modern Naval Architects use a variety of computer design tools to explore feasible options for clean sheet ship designs. Under the Naval Sea Systems Command (NAVSEA), the Naval Surface Warfare Center, Carderock Division (NSWCCD) has created computer tools for ship design and analysis purposes. This paper presents an overview of some of these tools, specifically the Advanced Ship and Submarine Evaluation Tool (ASSET) version 6.3 and the Integrated Hull Design Environment (IHDE). This paper provides a detailed explanation of a ship design using these advanced tools and presents methods for optimizing the performance of the hullform, the selection of engines for fuel efficiency, and the loading of engines for fuel efficiency. The detailed ship design explores the design space given a set of specific requirements for a cruiser-type naval vessel. The hullform optimization technique reduces a ships residual resistance by using both ASSET and IHDE in a Design of Experiments (DoE) approach to reaching an optimum solution. The paper will provide a detailed example resulting in a 12% reduction in total ship drag by implementing this technique on a previously designed hullform. The reduction of drag results in a proportional reduction in the amount of fuel used to push the ship through the water. The engine selection optimization technique uses MATLAB to calculate the ideal engines to use for fuel minimization. For a given speed-time or power-time profile, the code will evaluate hundreds of combinations of engines and provide the optimum engine combination and engine loading for minimizing the total fuel consumption. This optimization has the potential to reduce fuel consumption of current naval warships by upwards of 30%.
Thesis: S.M., Massachusetts Institute of Technology, Engineering Systems Division, 2014.; Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.; Cataloged from PDF version of thesis.; Includes bibliographical references (pages 163-164).
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/1721.1/921242014-01-01T00:00:00Z